Opossum, the general name of the family di-delpMdm of the order of marsupials, the sarigue of the French. They are confined to America, extending from the middle states to Buenos Ayres on the south, and, with a few exceptions, to the east of the Andes. Some are as large as a domestic cat, but most are no larger than a rat. The form is rat-like, but the muzzle is longer, ending in a distinct naked muffle; the ears are large, membranous, rounded, and almost naked; the body rather stout; tail generally very long, with only a few minute scattered hairs, except at the root, and powerfully prehensile; the feet five-toed, plantigrade, naked beneath; all the toes with moderate claws, except the inner one of the hind foot; the hind thumb is distinct, and opposable to the other toes; mammae from 9 to 13, the odd one being in the centre of a ring formed by the others. The teeth are 50: incisors 5/1, 5/4, cylindrical, arranged in a semicircle, the foremost two the longest; canines 1/1-1/1, the upper the longest; premolars 3/3-3/3, two-rooted, compressed, and pointed; molars 4/4-4/4, three-rooted, tubercular, with five prickly cusps. The stomach is simple, and the caecum moderately long. Opossums are mostly nocturnal, hiding among the foliage by day, and active at night in search of food.

They are divided into two sections, according to the presence or absence of the pouch. Among those which have a well developed pouch belongs the common opossum (didelphis Virginiana, Shaw), about 20 in. long, and the tail 15 in. additional; hair long, soft, and woolly, whitish at the roots and brownish at the tip, giving the animal a dusky color; long white hairs are mingled with the ordinary fur of the body; face near the snout white, dusky around the eyes; ears black, with the base and margin whitish; legs, feet, and basal portion of tail brownish black. The mouth is wide, the jaws weak, the eyes small and high on the forehead, whiskers stiff, and tail capable of involution only on the under side. The opossum is sometimes active by day, but generally prefers to prowl in bright and still nights around plantations, rice fields, and low swampy places. The gait on the ground is slow, heavy, and pacing, but on trees, to which it takes when pursued, its motions are very lively; the sense of smell is acute; it is fond of lying on its back in the sun for hours. It is generally solitary, unless when bringing up a family.

The teeth indicate its omnivorous character; its food consists of corn, nuts, berries, persimmons, roots, tender shoots, insects, young birds and eggs, mice, and similar small quadrupeds; sometimes it will kill poultry, sucking the blood but not eating the flesh, though it is far less mischievous in this respect than the mink, weasel, and skunk; it is very expert in climbing in search of food, hanging by the tail or swinging by it from one tree to another. When caught it feigns death, and will sometimes in this condition bear considerable torture without exhibiting signs of life, all the time watching its opportunity to bite or escape; hence the expression "playing 'possum;" when wounded, it is very tenacious of life. The flesh is edible; the skin is fetid; the hair is dyed by the Indians, and is woven into girdles and other ornaments. When taken young, it is easily domesticated. It is very prolific, bringing forth 12 to 16 at a birth, in the early part of March, May, and July, in South Carolina, and having even a fourth brood further south.

The nest is made of dried grass, under a bush or root of a tree, and sometimes the Florida rat or the squirrel is forced to give up its lodging place; the time of gestation is 15 or 16 days; the young when first born are about half an inch long, blind and naked; the mother places them with her mouth in the pouch, which she holds open with her fore feet, where they soon attach themselves very firmly, each animal to its teat; they grow very rapidly, increasing nearly tenfold in weight during the first week, and are very tenacious of life; when about five weeks old, or of the size of a mouse, they leave the pouch, returning to it to suck, or at the approach of danger; they remain with their mother about two months; the mother is very fond of her young, which are carried about, twisting their tails around that of the parent, and clinging to various parts of her body; the females are prolific at a year old. This species is found from the Hudson river to beyond the Missouri; it is replaced in Mexico, Texas, and California by the D. Californica (Benn.), a smaller animal with a comparatively longer tail, much darker on the body and limbs, the head dusky with a brown streak through the eye, chin and throat sooty, and the ears black.

The crab-eating opossum (D. cancrivora, Gmel.) inhabits chiefly the northern parts of South America; the color is a nearly uniform brownish black, with the upper half of the tail whitish; the hair is glossy but harsh, very long (even to 3 in. on the back), and dirty yellowish white next the skin; the total length is about 32 in., of which the tail is one half. It prefers the swampy regions of Guiana, where small crabs abound, of which it is very fond; it also eats small birds, reptiles, and insects; its flesh is eaten by the Indians, and is said to resemble that of the hare. Several other species of this section are described by Water-house. - In the section containing opossums in which the pouch is rudimentary or entirely wanting, the size is smaller, and the young are carried principally on the mother's back, retaining their position by entwining their tails around that of the parent; here also belong about 20 species. Remains of opossums have been founcl in the calcareous caverns of Brazil, nearly allied to, if not identical with, existing species; Cuvier discovered in the gypsum quarries of Montmartre, of the Paris basin, an almost entire skeleton of a didelphis, which shows the existence of marsupials in Europe in the eocene geological period, contemporaneous with the anoplotherium paloeotherium, and other extinct ungulates. (See Yapock).

Common Opossum (Didelphis Virginiana).

Common Opossum (Didelphis Virginiana).